Highlight empty lines

Closes #19484

app/assets/stylesheets/framework/highlight.scss

@@ -6,11 +6,11 @@
   table-layout: fixed;
 
   pre {
-    padding: 10px;
+    padding: 10px 0;
     border: none;
     border-radius: 0;
     font-family: $monospace_font;
-    font-size: $code_font_size !important;
+    font-size: 0;
     line-height: $code_line_height !important;
     margin: 0;
     overflow: auto;
@@ -21,12 +21,18 @@
 
     code {
       font-family: $monospace_font;
+      font-size: 0;
       white-space: pre;
       word-wrap: normal;
       padding: 0;
 
       .line {
         display: inline-block;
+        width: 100%;
+        min-height: 19px;
+        padding-left: 10px;
+        padding-right: 10px;
+        font-size: $code_font_size;
       }
     }
   }

app/views/projects/blob/_editor.html.haml

@@ -24,7 +24,7 @@
       .encoding-selector
         = select_tag :encoding, options_for_select([ "base64", "text" ], "text"), class: 'select2'
 
-  .file-content.code
+  .file-editor.code
     %pre.js-edit-mode-pane#editor #{params[:content] || local_assigns[:blob_data]}
     - if local_assigns[:path]
       .js-edit-mode-pane#preview.hide

spec/features/projects/files/project_owner_creates_license_file_spec.rb

@@ -23,7 +23,7 @@ feature 'project owner creates a license file', feature: true, js: true do
 
     select_template('MIT License')
 
-    file_content = find('.file-content')
+    file_content = first('.file-editor')
     expect(file_content).to have_content('The MIT License (MIT)')
     expect(file_content).to have_content("Copyright (c) #{Time.now.year} #{project.namespace.human_name}")
 
@@ -46,7 +46,7 @@ feature 'project owner creates a license file', feature: true, js: true do
 
     select_template('MIT License')
 
-    file_content = find('.file-content')
+    file_content = first('.file-editor')
     expect(file_content).to have_content('The MIT License (MIT)')
     expect(file_content).to have_content("Copyright (c) #{Time.now.year} #{project.namespace.human_name}")
 

spec/features/projects/files/project_owner_sees_link_to_create_license_file_in_empty_project_spec.rb

@@ -22,7 +22,7 @@ feature 'project owner sees a link to create a license file in empty project', f
 
     select_template('MIT License')
 
-    file_content = find('.file-content')
+    file_content = first('.file-editor')
     expect(file_content).to have_content('The MIT License (MIT)')
     expect(file_content).to have_content("Copyright (c) #{Time.now.year} #{project.namespace.human_name}")